The field of medical radiography has undergone profound changes in the past few years. In particular, the development of new types of recording media using photoluminescent memory plates, well known by the name of "phosphor plates", has enabled digital medical imaging to be developed. Traditionally, radiographic images were obtained on photosensitive plates which, after processing in photographic treatment baths, enabled the radiographic image to be displayed. Technological developments in the past few years with regard to image processing have made it possible to envisage obtaining radiographic images which can be exploited from digital data.
A digital medical imaging unit is associated with a radiography system using "phosphor cartridges", that is to say cartridges provided with photoluminescent memory plates used to form a latent analogue radiographic image.
In order to be able to exploit the latent image contained in the photoluminescent memory plate, the cartridge is inserted into a reading device in which the plate is extracted from the cartridge and then scanned with a reading beam so as to excite the plate locally. This excitation causes a photoluminescent emission which is a function of the irradiation received by the plate. By means of a photosensitive sensor, the reading device converts the intensity of the radiation emitted by the plate into an analogue electrical signal which is then converted into digital data. By scanning the plate, the reading device therefore supplies, for each plate, a digital representation of the information carried by the photoluminescent memory plate. The reading device is very often associated with an automatic cartridge dispenser enabling a plurality of cartridges to be disposed at the entry to the reading device. After the processing of a cartridge by the reading device, the latter erases any residual information on the plate and returns the cartridge to the dispenser and takes therefrom a new cartridge in order to process it.
The digital representation coming from the reading device is then processed by a suitable digital processing unit provided with distinct processing algorithms dependent on the type of radiographic images recorded on the photoluminescent memory plate. To do this, information relating to the type of radiographic examination carried out with the cartridge concerned is supplied to the processing unit.
The medical imaging unit also comprises a workstation which, after receipt of the digital medical images, makes it possible to edit the various images contained in the memory of the processing unit.
A description will now be given of the conventional use of a digital medical imaging unit. When it is desired to carry out a radiographic examination of a patient by means of a digital medical imaging unit, the information required for the identification of the patient is first of all introduced into the computer. In general the surname of the patient and his first name are introduced, sometimes his sex and his age. A unique identification number, which can be coded and printed in the form of a bar code on labels, is made to correspond to this information. Normally, each phosphor cartridge is identified unequivocally in order to be able to be recognized by the processing unit. In one particularly advantageous embodiment, the cartridges are identified by means of a bar code. During the radiographic examination it is necessary to introduce into the processing unit the type of examination recorded in each cartridge. Advantageously, in some medical imaging units, this information can be introduced into the processing unit by means of a bar code reader, preferably portable, which will capture the information directly at the time of the radiographic examination. In this way any possible mixing up of the cartridges is avoided when the examination requires more than one cartridge for the patient.
In a particularly advantageous known embodiment, at the time of exposure to x-rays, there are entered with a bar code reader, preferably portable, of the code of the patient, the code of the cartridge, the type of examination or part of the patient observed (cranium, thorax, shoulder, hand, etc), the type of projection (side, profile, antero-posterior or AP, postero-anterior or PA), the orientation (landscape, portrait) with a view to the correct display on the screen or at the time of editing and optionally the position of the patient (lying down, standing, semi-seated), the name of the person carrying out the examination and the technical data (kV, mAS, distance). Once the data have been entered, a validation data item or End is sent to the processing unit.
After the exposure of the cartridges to x-rays and the recording, in the processing unit, of the data relating to the examinations, the cartridges are inserted in the automatic dispenser associated with the reading device so as to obtain a digital representation of each of the radiographic images recorded in each of the cartridges.
By means of the information entered relating to each exposure, the processing unit applies the appropriate processing algorithms to the digital information and associates a patient with each of the cartridges.
Then, using a workstation, an operator is able to edit, on an editing medium, one after the other, the various images contained in the processing unit. In an automatic operating mode of the workstation, the printer produces one image from the processing unit per page of the editing medium as the processing unit delivers a processed digital image. Advantageously, provision can be made for the dimension of the editing medium to be determined by default either by the size of the cartridge or by the type of examination.
For certain types of examination, it is desirable to group together several radiographs on a single editing page. To do this, an operator manually controls the workstation in order to associate, with one and the same page of an editing medium, the digital images to be edited on this page. This type of editing requires human intervention. An operator must, before commencing the editing of several images on a single medium, verify that all the digital images are available. If the images to be edited are not all available, the operator must either wait until all the images are available or subsequently recommence the entry relating to the editing. These operations are tedious and take up time, and there is a risk of transposing certain radiographs.